Thermal expansion and contraction of soldered connections explains it all.

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I believe it was all related to fan problems. Do no understand why they stopped working well nevertheless.
I was thinking maybe thermal pads are olds/dirty, do you believe a dot (very little) of thermal paste might help? Finding new thermal pads is too difficult here to be an option.
Lastly if everything else fails I am working with physicist. They told me electronic molds can sometimes be "saved" by heating in a hoven (with controlled temperature). As I said, if nothing else works... Anyone tried this once ?

Baking seems pretty well documented for GPU. I guess it is worth the try (in crossfire with prayers ) if nothing else works. I will let you know...
One thing : the main video adapter has a metal back plate with cooling pads that I need to remove to bake. I never managed to remove it. Any advice ???

I tend to use a small scredrive and push posts through using that, just be careful and take your time.

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Sorry I am not sure I understand you. "push post through" it is like making a small gap with tension then go deeper ?
you mean a flat screwdriver right ? NOT a phillips ?
you use it as a lever I guess ? Seems a bit harsh to me...
How is fixed a backplate usually ? Is it glued, or screwed (I didn t see any screw) or does it differ from one card to another ? So far it seemed quite firmly attached so I never insisted.
I will try this week end but I am a bit worried, any detail would be great. Thanks a lot !

I mean I use one with a head small enough to fit through the mounting hole in the pcb and carefully push through. It tends to bend the backplate a little but not significantly and you can straighten it again.

I mean I use one with a head small enough to fit through the mounting hole in the pcb and carefully push through. It tends to bend the backplate a little but not significantly and you can straighten it again.

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wow thanks for fast answer I will check this. Here a picture of what I call "backplate"... It is the grey metallic part on the picture.

I mean I use one with a head small enough to fit through the mounting hole in the pcb and carefully push through. It tends to bend the backplate a little but not significantly and you can straighten it again.

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well, that s embarassing but I cannot manage to remove that grey plate on the picture. Is it even a backplate and do I need to remove it to bake it ? Problem is there are cooling pads between it and the card so I am afraid it will transfer all heat to the card... There is a black strip as can be seen on the picture, maybe it is easier pulling this ? The other card just has the regular X instead of that plate.
Sorry I insist but I am not confident using too much strength...
Any though ?
thanks again

Yes, can be pretty sticky sometimes. Its persistence is simply due to ages and ages of combination 'close proximity + heat'; once freed it won't be that difficult anymore.

Might check reverse side's free first, though, just to be sure. That's also where you'd push with screwdriver tip, btw. Can also use it as a lever; insert between pcb and heatsink right next to one of the four raisers/holes. There's no ICs or traces this close, so can safely rotate tip; pcb scratches won't matter. If one corner is difficult, try another, same when using the push-on-reverse-side method.

OK I did it. It was extremly hardly glued so I had to infiltrate isoprpyl alcohol over the sticker joint to soften the glue, create a gap then slowly add more and extend the gap with little tension. It finally stopped resisted and the backplate is separated now (a bit less smoothly than I planned...). I hope nothing wrong happened but I do not want to try it now. We will see next week if baking will saved my main GPU.
THANKS t456 and THANKS Meaker, you were extremly kind, helpful and patient.
Bow